Assessing Renal Function

Question 1

What are 4 causes of increased blood urea nitrogen?

Answer 1

1. Post-prandial
2. Dehydration
3. GI bleeding
4. Catabolic drugs

Question 2

What are 3 causes of decreased blood urea nitrogen?

Answer 2

1. Malnutrition
2. Severe burns
3. Hepatic dysfunction

Question 3

Creatinine increases with __1__ and __2__.

Answer 3

1. Muscle mass

2. High protein diet

Question 4

In which 2 breeds are creatinine levels naturally high?

Answer 4

1. Birmans

2. Greyhounds

Question 5

Which is more accurate, BUN or creatinine?

Answer 5

Creatinine

Question 6

What does SDMA stand for?

Answer 6

Symmetric dimethylarginine

Question 7

When can SDMA detect renal dysfunction?

Answer 7

At 40% loss of function

Question 8

Which of the following is influenced by muscle mass: creatinine, BUN, or SDMA?

Answer 8

Creatinine

Question 9

When does renal azotemic develop?

Answer 9

With 75% loss of function

Question 10

What are the 4 substances used for clearance assays to measure GFR?

Answer 10

1. Inulin
2. Iohexol
3. Creatinine
4. Radioisotopes

Question 11

What is the easiest and most commonly used substance for clearance assays?

Answer 11

Iohexol

Question 12

What are 4 indications for using a clearance assay?

Answer 12

1. Identifying occult renal failure prior to starting nephrotoxic drugs
2. Assessing renal function in non-azotemic PU/PD patients
3. Screening patients with familial history of kidney disease
4. Investigating discrepancies in BUN and creatinine

Question 13

What is one benefit to renal scintigraphy?

Answer 13

Ability to measure each individual kidney’s GFR

Question 14

What are the disadvantages of renal scintigraphy?

Answer 14

1. Expensive
2. Special facilities
3. Limited availability

Question 15

What are the sources of proteinuria?

Answer 15

1. Physiological - fever, seizures, intense physical activity
2. Non-urinary - genital tract inflammation (vaginitis, prostatitis), hyperglobulinemia (multiple myeloma), hemoglobinemia (hemolytic anemia)
3. Urinary - glomerular disease, uroliths, UTIs, bladder tumors

Question 16

The glomerulus allows passage of molecules less than ___-___ kDa

Answer 16

67-70 kDa

Question 17

Resorption of most molecules (glucose, amino acids, HCO3, electrolytes) occurs where within the nephron?

Answer 17

Proximal tubule

Question 18

What are 2 causes of renal proteinuria?

Answer 18

1. Increased loss of glomeruli

2. Decreased reabsorption in tubules

Question 19

A dip stick can be used to quantify protein loss but primarily detects what?

Answer 19

Albumin

Question 20

Which has more protein loss: (+) protein with USG 1.040 or (+) protein with USG 1.008?

Answer 20

(+) protein with USG 1.008

Question 21

What is a normal urine protein/creatinine ratio in the dog?

Answer 21

< 0.5

Question 22

What is a normal urine protein/creatinine ratio in the cat?

Answer 22

< 0.4

Question 23

What are the 3 main roles of the renal tubules?

Answer 23

1. Water conservation
2. Acid/base balance
3. Reabsorption of metabolites

Question 24

What is the renal tubular reabsorption threshold for glucose in the cat?

Answer 24

290 mg/dL

Question 25

What is the renal tubular reabsorption threshold for glucose in the dog?

Answer 25

180-220 mg/dL

Question 26

On average, the kidneys filter about ____ litters of water/day.

Answer 26

100 L

Question 27

Of that 100 litters, less than ___% is lost to the urine.

Answer 27

1%

Question 28

What is the specific gravity a ratio of?

Answer 28

Ratio of the weight of urine vs. weight of an equal amount of water

Question 29

What is the isosthenuric range of urine?

Answer 29

1.008 - 1.012

Question 30

At what concentration is urine equal to the osmolality of plasma?

Answer 30

1.008 - 1.012

Question 31

What do you call urine with a USG of < 1.008?

Answer 31

Hyposthenuric

Question 32

What are 4 drugs that cause the urine to be dilute?

Answer 32

1. Steroids 2. Diuretics 3. Colloids 4. Anti-epileptics

Question 33

What are 4 concurrent diseases that might affect the USG?

Answer 33

1. Dehydration 2. Endocrine diseases (DM, cushing's, addison's) 3. Electrolyte abnormalities (hypercalcemia) 4. Infections (pyometra, pyelonephritis, leptospirosis)

Question 34

What 3 things does one need to concentrate their urine?

Answer 34

1. ADH 2. ADH receptors 3. Functional kidneys

Question 35

After running a water deprivation test and getting dilute urine, what is your next step?

Answer 35

Administer DDAVP (synthetic ADH)

Question 36

If you get a response with synthetic ADH, what is your diagnosis?

Answer 36

Central DI

Question 37

If you do not get a response with synthetic ADH, what is your diagnosis?

Answer 37

Nephrogenic DI

Question 38

Because the water deprivation test is no longer recommended by most internists anymore, what is an alternative to test water conservation of the renal tubules?

Answer 38

Vasopressin test